title: Substituted 2,2'-bipyrroles and pyrrolylfuransviaintermediate isoxazolylpyrroles.
abstract: We describe a new synthesis of the 3-chloro-(4'-methoxy)-2,2'-pyrrolylfuran segment (3) of (+)- roseophilin. The route exploits a isoxazoylpyrrole intermediate, wherein the isoxazole ring serves as a β-diketone equivalent and a directing group for palladium catalyzed chlorination of the attached pyrrole. Subsequent reduction of the N-O bond and acid promoted cyclization afords roseophilin segment3bin five steps and 19% overall yield. This strategy was extended to the synthesis of 3-chloro-(4'-alkoxy)-2,2'-pyrrolylfurans (16a-c) and 4-alkoxy-2,2'-bipyrroles (20a-c), which are building blocks to synthesize bioactive prodiginine natural products and their congeners.
authors.affiliation: Department of Chemistry and Biochemistry, University of California at Los Angeles, 607 Charles E. Young Drive East, Los Angeles, CA 90095, United States.
authors.forename: James H
authors.initials: JH
authors.lastname: Frederich
authors.forename: Jennifer K
authors.initials: JK
authors.lastname: Matsui
authors.forename: Randy O
authors.initials: RO
authors.lastname: Chang
authors.forename: Patrick G
authors.initials: PG
authors.lastname: Harran
keywords: 3-alkoxyfurans; 3-chloro-(4′-alkoxy)-2,2′-pyrrolylfuran; C–H bond functionalization; isoxazole; prodiginine